Question

Question about stream operation delay.
On page 268 (SICP 2nd) has this code:
(define (memo-proc proc)
(let ((already-run? false) (result false))
(lambda ()
(if (not already-run?)
(begin (set! result (proc))
(set! already-run? true)
result)
result))))
In this process, it will test whether already-run? Is true, but every time the process memo-proc would set already-run? to false, how can this problem achieve it’s goal?

Answer 1

@e.mccormick

Answer 2

@e.mccormick